Utilization of gamma and e-beam irradiation in the treatment of waste sludge from a drinking water treatment plant

Abstract

An increasing production of drinking water and a significant amount of waste in the form of treated sludge can lead to a serious environmental problem. The high organic content in the sludge, together with the high summer temperatures, results in the enhanced activity of sludge microorganisms, causing severe can cause serious biological pollution. Also, there is a danger due to the potential presence of polyacrylamide, which is very harmful to human health and the environment. In this paper, the influence of different types of ionizing radiation (gamma and e-beam) on microorganisms inactivation in waste sludge from drinking water treatment plants was investigated. The content of heavy metals and polyacrylamide before and after irradiation was determined. It was concluded that the content of heavy metals in the waste sludge obtained from the drinking water treatment plant is significantly lower than the limit values. The concentration of acrylamide, both before and after irradiation, was limit value for sludge to be used as fertilizer. It was found that the dose of 25 kGy inactivates all pathogens in all samples collected directly after coagulation, flocculation, and sedimentation and that the dose of 10 kGy is sufficient to inactivate all pathogens from dewatered samples previously treated with lime. In both cases, the number of microorganisms decreases sharply with increasing radiation dose.